1. Field of the Invention
The present invention relates to what is called a front-opening interface mechanical standard (FIMS) system, that is, a load port apparatus, which is used for transferring, from one semiconductor processing apparatus to another semiconductor processing apparatus, wafers held in a sealed-type transport container called a pod during a semiconductor manufacturing process and the like. More particularly, the present invention relates to a main-unit structure of a load port apparatus, which contributes to weight reduction of the structure as a whole.
2. Description of the Related Art
In recent years, in a general semiconductor manufacturing process, cleanliness is managed throughout the entire process by maintaining a highly clean state in only the following three spaces: inner spaces of various processing apparatuses; an inner space of a pod capable of housing wafers and transporting the wafers from one processing apparatus to another processing apparatus; and mini-environments in which the wafers are exchanged between the pod and the respective processing apparatuses. Such a pod includes a main-unit portion which houses wafers therein and which has a wafer-insertion-and-removal opening formed in one side surface, and a lid which makes the inside of the pod serve as a sealed space by closing the opening. Further, a structure that defines the mini-environment includes an opening portion capable of facing the above-mentioned opening of the pod and a second opening portion arranged on a semiconductor processing-apparatus side so as to face the opening portion.
The load port apparatus includes a member as a partition wall provided with the opening portion, that is, a wall called a side base, a door for closing the opening portion, a door drive mechanism for controlling operation of the door, and a placing table on which the pod is placed. A placing base on the placing table on which the pod is actually placed is capable of supporting the pod in such a manner as to face the opening of the pod and the opening portion each other, and brings the lid of the pod close to or separated from the door together with the pod itself. The door is capable of holding the lid of the pod, and retracted below the space between the opening portion and the second opening portion by the door drive mechanism while holding the lid. A robot is arranged in the mini-environment, and the robot is capable of entering into and retracting from the inside of the pod through the opening portion and the opening of the pod, and transfers wafers between the inside of the pod and the semiconductor processing apparatus also through the second opening portion.
In semiconductor manufacturing steps, an increase in a bore diameter of wafers to be used has been promoted for higher productivity. In accordance therewith, each of the above-mentioned pod, mini-environment, and space in the processing apparatus are also upsized. For example, the load port apparatus disclosed in Japanese Patent Application Laid-Open No. 2003-347387 enters a functionable state by fixing a side base, which is a vertical wall, to one side surface of a transport chamber of a processing apparatus. The one side surface is generally referred to as an attachment surface. Here, as the bore diameter of wafers increases, an enlargement of the opening portion of the load port apparatus and upsizing of the door in accordance therewith are also demanded. Such upsizing of the door involves an increase in weight of the door, and the door drive mechanism is required to have a larger actuation force according to the increased weight of the door.
Here, a side base disclosed in Japanese Patent Application Laid-Open No. 2003-347387 is formed of a single flat plate-like member. The side base is required to support the door and the door drive mechanism, and simultaneously have a rigidity sufficient against a dynamic load generated at the time of operations of the door and the door drive mechanism, that is, what is called a moment. However, along with the upsizing of the door and the like in recent years, it has become gradually difficult to secure the sufficient rigidity in conventional structures. Further, when such an attempt is made as to increase a thickness of the side base for the purpose of securing the sufficient rigidity, there is a risk that a weight of the side base increases, and it becomes more difficult to appropriately install the load port apparatus with respect to the processing apparatus.